Electrical system



atente ay 9 it ELIEC'EC SYSTEM Samuel E. dd, Chicago, l[ll., asailgnor, by me assignments, to Bendix Radio Coration, ft ware timore, Md, a? corporation of Welsh.

dppiicationmecember 19, 1936, Serial No. name This invention relates to the use of the power lines of a lighting system for the transmission of radio and telephone messages and the like, and'is diagrammatically illustrated as embodied in a system for utilizing the lighting system or part of the lighting system of a boat for the transmission of messages, as for example from the bridge to the engine room. An important object isto so arrange the system that the transmission of messages is not interfered with by the operation of the lights, and preferably so it will not be afiected by the opening and closing of the switches controlling the lights, and so that the transmitter and receiver can be readily and quicklyconnected to and disconnected lul S.

i from the system at difierent points.

Preferably the system has the lights connected in parallel across the conductors carrying the current, for examplethe conductors for the direct current used in lighting boats. The transmitter and the receiver or receivers are coupled respectively, for example inductively, to auxiliary conductors each of which is connected between a pair of condensers connected in series between the main conductors of the lighting system. The auxiliary conductors are also electrically connected to complete the transmission circuit, for example by grounding them to the metal hull of the boat. It the lighting system includes any control switches, condensers are connected around them in parallel with them.

In a modification of the above-described system, the transmitter and one or more receivers are connected as described between condensers connected in pairs in series between the conductors of part of an alternating current lightpart of an alternating current lighting system.

In the arrangement of Figure 1, a direct-current generator g is used to supply current to the.

nected in parallel between the conductors in and l2, and suitable control switches it are provided where desired, the one illustrated being adapted when opened to cut ofl all but the first two lights M.

Several auxiliary connections are also connected in parallel between the conductors iii and I2. Each of these includes a pair of condensers it connected in series by having one set of plates of each connected to one of the conductors id or it and by having the other sets of plates connected by a lead 20. The mid-points of the leads 2% are connected to auxiliary conductors 22, 2 5, which are electrically connected, for example by being grounded at 25, 23 to the metal hull of the boat.

The auxiliary conductor 22 has coupled (preferably inductively) thereto a transmitter T, which may be a radio receiver or a telephone set or other means of generating messages. The illustrated transmitter includes a microphone MB on the bridge of the boat, connected to an amplifier 32 connected to the primary winding id of a transformer, thesecondary winding 36 of which is connected into the auxiliary conductor 22 between the lead 20 and the ground it. The condensers it and the lead it may be included in a single plug adapted to be plugged in the usual way into a wall socket or the like.

Coupled (preferably inductively to each of the other auxiliary conductors it is a receiver R. The receiver illustrated in Figure 1 includes a telephone receiver dd having its coil it connected in series with the secondary winding tit of a transformer which has its primary winding tfi ccnnected into the auxilibry conductor M.

If any of the switches it are so positioned that they would interfere with the transmission of messages between the transmitter T and the 'receivers R, condensers 5B are connected around them in parallel therewith.

.It will be seen that all of the current in the lighting circuit Gililll2-G is retained in that circuit and does not interfere with the transmission of messages. However, the two conductors it and it at the same time together form Figure 1, except that the side of the message circuit opposite the conductors Ill] and H2 (cor-= responding to conductors l0 and I2) is a special conductor or metallic ground 12G forming the equivalent of the ground 26, and used where it is not desired to use an ordinary ground for any reason.

Hit

The arrangement of Figure 3 may be used where it is desired to utilize part of an alternating-current lighting system to transmit messages, as for example when it is desired to transmit programs from a central radio receiving set (serving as a transmitter) to loud speakers in the rooms of a hotel or apartment house, serving as receivers.

In this case, the leads 2! and 3) of the regular lighting system are connected, where they enter the building, to the ends of a primary winding 60 of a transformer having a secondary winding 82 arranged with its center point grounded through a lead 64, for example to the frame of the building or to the water pipes, as indicated at 66. The ends of the secondary winding 62 are connected to interior conductors 3M and 3H, across which the lights I! are connected in parallel. The transmitter and receiver are shown connected to the conductors 3H] and M2 between condensers I8, the same as they are connected to the conductors l0 and I2 in Figure 1, and are electrically connected to each other and to themid point of the secondary winding 62, by being grounded at 26 and 28 as before.

The condensers is are so constructed that they have a high reactance at the low frequency of the line voltage and comparatively low reactance at the sound frequency range.

While three illustrative arrangements have been described in detail, it is not my intention to limit the scope of the invention to those particular arrangements, or otherwise than by the terms of the appended claims.

I claim:

1. In an electrical system having a source of electric power and a lighting circuit including two conductors connected to said source and a plurality of electric lights connected in parallel between said conduct'ors, a communication system comprising a plurality of connections in parallel between said conductors and each including a pair of condensers having one set of plates connected to said conductors respectively and having a lead connecting their other sets of plates electrically together, grounded auxiliary conductors connected respectively to said leads, a transmitter inductively coupled to one of said grounded auxiliary conductors, and a receiver inductively coupled to another of said grounded auxiliary conductors.

2. In an electrical system having a source of electric power and a lighting circuit including two conductors connected to said source and a plurality of electric lights connected in parallel between said conductors, a communication system comprising a plurality of connections in' parallel between saidconductors and each including a pair of condensers having one set of plates connected to said conductors respectively and having a lead connecting their other sets of plates electrically together, auxiliary conductors connected respectively to said leads, a transmitter coupled to one of said auxiliary conductors, a receiver coupled to another of said auxiliary conductors, and means electrically-connecting said auxiliary conductors to complete a circuit therethrough and through the'said two conductors which is independent of said lighting circuit.

In an electrical system having a power line ha -ng two conductors connected to the primary win ing of a transformer, a secondary winding for said transformer having its mid point grounded and a pair of conductors connected to the ends of said secondary winding, electric lights connected in parallel between said conductors, a communication system comprising auxiliary connections in parallel between said conductors and each including two condensers in series with each other, grounded auxiliary conductors each connected to one of said auxiliary connections between said condensers therein, a transmitter inductively coupled to one of said auxiliary conductors, and a receiver inductively coupled to another of said auxiliary conductors.

4. In an electrical system having a power line having two conductors connected to the primary winding of a transformer, a secondary winding for said transformer, a pair of conductors connected to the ends of said secondary winding and electric lights connected in parallel between said conductors, a communication system comprising auxiliary connections in parallel between said conductors and each including two condensers in series with each other, auxiliary conductors each connected to one of said auxiliary connections between said condensers therein, a transmitter coupled to one of said auxiliary conductors, a receiver coupled to another of said auxiliary conductors, and means for electrically connecting said auxiliary conductors and the mid point of said secondary winding. I

5. In an electrical system having a source of electric power and a lighting circuit including two conductors connected to said source and a plurality of electric lights connected in parallel between said conductors, a communication system comprising a plurality of connections in parallel between said conductors and each including a pair of condensers having one 'set of plates connected to said conductors respectively and having a lead connecting their other sets of plates electrically together, grounded auxiliary conductors connected respectively to said leads, a transmitter inductively coupled to one of said grounded auxiliary conductors, and a receiver inductively coupled to'another of said grounded auxiliary conductors, said lighting circuit conductors being provided with a switch for opening and closing of the lighting circuit, together with a condenser connected in parallel around said switch, whereby the opening and closing of the switch does not aflEect the transmission of messages from said transmitter to said receiver.

6. In an; electrical system having a source of electric power and a lighting circuit including two conductors connected to said source and a plurality of electric lights connected in parallel between said conductors, a communication system comprising a plurality of connections in parallel between said conductors and each including a pair of condensers having one set of plates connected to said conductors respectively and having a lead connecting their other sets of plates electrically together, auxiliary conductors connected respectively to said'leads, a transmitter coupled to one of said auxiliary conductors, a receiver coupled to another of said auxiliary conductors, and means electrically connecting said auxiliary conductors to complete a circuit therethrough and through the said two conductors which is independent of said lighting circuit, said lighting circuit conductors being provided with a switch for opening and closing of the lighting circuit, together with a condenser connected in parallel around said switch, whereby the opening and closing of the switch does not aifect the transmission of messages from said transmitter to said receiver.

SAMUEL E. ADAIR; 

